En Face Optical Coherence Tomography Illustrates the Trizonal Distribution of Drusen and Subretinal Drusenoid Deposits in the Macula

Abstract

PurposeTo analyze the topographic distribution of macular drusen and subretinal drusenoid deposits (SDD) using single capture en face spectral domain optical coherence tomography (SD-OCT) imaging. DesignRetrospective case series. MethodsAnalysis of 33 eyes of 20 patients with evidence of SDD. Structural en face OCT images were reconstructed using a 40µ thick slab positioned from 48 to 88 µm above Bruch's membrane. The Early Treatment of Diabetic Retinopathy Study (ETDRS) grid and a rod/cone density map were overlaid upon the en face OCT images and the distribution of different subtypes of SDD and macular drusen were assessed. ResultsA total of 31 eyes (94%) showed a trizonal distribution pattern of drusen and SDD. Whereas small to large drusen tended to aggregate in the central circle, dot SDD predominated in the inner ring and the inner portion of the outer ring of the ETDRS grid and ribbon SDD localized to the outer ring and outside the ETDRS grid. Of note, drusen colocalized to the region of greatest cone density, while ribbon SDD colocalized to the area of greatest rod density. The dot SDD mapped to the intermediate region with mixed rod and cone representation. ConclusionDot and ribbon subtypes of SDD and macular drusen show a characteristic trizonal distribution. The locations of these lesions co-localize according to the different densities of the cones and rods in the retina and may reflect varying pathophysiological activities of these photoreceptor subtypes.